From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1424751AbcFHKV3 (ORCPT ); Wed, 8 Jun 2016 06:21:29 -0400 Received: from mail-lf0-f54.google.com ([209.85.215.54]:33812 "EHLO mail-lf0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161938AbcFHKVZ (ORCPT ); Wed, 8 Jun 2016 06:21:25 -0400 Subject: Re: [PATCH V8 5/9] pci, acpi: add acpi hook to assign domain number. To: Bjorn Helgaas References: <1464621262-26770-1-git-send-email-tn@semihalf.com> <1464621262-26770-6-git-send-email-tn@semihalf.com> <20160608001559.GD4759@localhost> Cc: arnd@arndb.de, will.deacon@arm.com, catalin.marinas@arm.com, rafael@kernel.org, hanjun.guo@linaro.org, Lorenzo.Pieralisi@arm.com, okaya@codeaurora.org, jchandra@broadcom.com, robert.richter@caviumnetworks.com, mw@semihalf.com, Liviu.Dudau@arm.com, ddaney@caviumnetworks.com, wangyijing@huawei.com, Suravee.Suthikulpanit@amd.com, msalter@redhat.com, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linaro-acpi@lists.linaro.org, jcm@redhat.com, andrea.gallo@linaro.org, dhdang@apm.com, jeremy.linton@arm.com, liudongdong3@huawei.com, cov@codeaurora.org From: Tomasz Nowicki Message-ID: <5757F19F.6020200@semihalf.com> Date: Wed, 8 Jun 2016 12:21:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <20160608001559.GD4759@localhost> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Bjorn, On 08.06.2016 02:15, Bjorn Helgaas wrote: > Hi Tomasz, > > On Mon, May 30, 2016 at 05:14:18PM +0200, Tomasz Nowicki wrote: >> PCI core code provides a config option (CONFIG_PCI_DOMAINS_GENERIC) >> that allows assigning the PCI bus domain number generically by >> relying on device tree bindings, and falling back to a simple counter >> when the respective DT properties (ie "linux,pci-domain") are not >> specified in the host bridge device tree node. >> >> In a similar way, when a system is booted through ACPI, architectures >> that are selecting CONFIG_PCI_DOMAINS_GENERIC (ie ARM64) require kernel >> hooks to retrieve the domain number so that the PCI bus domain number >> set-up can be handled seamlessly with DT and ACPI in generic core code >> when CONFIG_PCI_DOMAINS_GENERIC is selected. >> >> Since currently it is not possible to retrieve a pointer to the PCI >> host bridge ACPI device backing the host bridge from core PCI code >> (which would allow retrieving the domain number in an arch agnostic >> way through the ACPI _SEG method), an arch specific ACPI hook has to >> be declared and implemented by all arches that rely on >> CONFIG_PCI_DOMAINS_GENERIC to retrieve the domain number and set it >> up in core PCI code. >> >> For the aforementioned reasons, this patch introduces a dummy >> acpi_pci_bus_domain_nr() hook in preparation for per-arch implementation >> of the same to retrieve the domain number on a per-arch basis when >> the system boots through ACPI. >> >> For the sake of code clarity the current code implementing generic >> domain number assignment (ie pci_bus_assign_domain_nr(), selected by >> CONFIG_PCI_DOMAINS_GENERIC) is reshuffled so that the code implementing >> the DT domain assignment function is stubbed out into a corresponding >> helper, so that DT and ACPI functions are clearly separated in >> preparation for arches acpi_pci_bus_domain_nr() implementations. >> >> Signed-off-by: Tomasz Nowicki >> Signed-off-by: Lorenzo Pieralisi >> --- >> drivers/pci/pci.c | 11 +++++++++-- >> include/linux/pci.h | 1 + >> 2 files changed, 10 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c >> index eb431b5..2b52178 100644 >> --- a/drivers/pci/pci.c >> +++ b/drivers/pci/pci.c >> @@ -7,6 +7,7 @@ >> * Copyright 1997 -- 2000 Martin Mares >> */ >> >> +#include >> #include >> #include >> #include >> @@ -4941,7 +4942,7 @@ int pci_get_new_domain_nr(void) >> } >> >> #ifdef CONFIG_PCI_DOMAINS_GENERIC >> -void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent) >> +static int of_pci_bus_domain_nr(struct device *parent) > > Can we do a little cleanup before this patch? > > - pci_bus_assign_domain_nr() is only used inside drivers/pci, so > maybe we move the prototype to drivers/pci/pci.h? pci_bus_assign_domain_nr() goes with pci_domain_nr() as an option for CONFIG_PCI_DOMAINS_GENERIC. pci_domain_nr() is used commonly outside drivers/pci so we would need to split these calls then, thus personally I think it would be better to keep both in inclue/linux/pci.h > > - I don't really like the style of calling a function that > internally assigns bus->domain_nr. Could we do something like > this instead? > > int pci_bus_domain_nr(...) > { > ... > return domain; > } > > ... pci_create_root_bus(...) > { > ... > b->domain_nr = pci_bus_domain_nr(...); We can. I do not see much difference between pci_bus_domain_nr() and pci_domain_nr() which we already have so how about calling it pci_bus_find_domain_nr instead? Lorenzo, any strong preference for it? > > That would be two new patches, if this makes sense. > > And this patch would only rename pci_bus_assign_domain_nr() to > of_pci_bus_domain_nr() and add the pci_bus_domain_nr() wrapper. Giving that we would keep prototypes in inclue/linux/pci.h 1. First patch would rename pci_bus_assign_domain_nr() to pci_bus_find_domain_nr() and it would return domain number so that we could do: ... pci_create_root_bus(...) { ... b->domain_nr = pci_bus_domain_nr(...); ... } 2. Second patch would transform pci_bus_find_domain_nr() to be the wrapper for of_pci_bus_domain_nr() 3. Third patch would add stub definition, the ARM64 definition and the new call acpi_pci_bus_domain_nr() in pci_bus_find_domain_nr() wrapper. Does this plan sound reasonable? > >> { >> static int use_dt_domains = -1; >> int domain = -1; >> @@ -4985,7 +4986,13 @@ void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent) >> domain = -1; >> } >> >> - bus->domain_nr = domain; >> + return domain; >> +} >> + >> +void pci_bus_assign_domain_nr(struct pci_bus *bus, struct device *parent) >> +{ >> + bus->domain_nr = acpi_disabled ? of_pci_bus_domain_nr(parent) : >> + acpi_pci_bus_domain_nr(bus); >> } >> #endif >> #endif >> diff --git a/include/linux/pci.h b/include/linux/pci.h >> index 12349de..bba4053 100644 >> --- a/include/linux/pci.h >> +++ b/include/linux/pci.h >> @@ -1390,6 +1390,7 @@ static inline int pci_domain_nr(struct pci_bus *bus) >> { >> return bus->domain_nr; >> } >> +static inline int acpi_pci_bus_domain_nr(struct pci_bus *bus) { return -1; } > > I would split the addition of acpi_pci_bus_domain_nr() to a separate > patch and include the ARM64 definition in that same patch. That patch > would only add this stub definition, the ARM64 definition, and the new > call in pci_bus_domain_nr(). OK Thanks, Tomasz